Elliptical waveguide connector



AUS l5, 1967 E. H. JOHNSON ETAL v 3,336,543

ELLIPTICAL WAVEGUIDE CONNECTOR Filed June 7, 1965 2 Sheets-Sheet l .515 ZZ 'E 50 f5 e0 l fr' Illlna Il Favsmm Z 2% 4' .50 jg j 53 2% /f/zey Aug. 15, 1967 E. H. JOHNSON' ETAL 3,335,543

ELLIPTICAL WAVEGUIDE CONNECTOR Filed June 7, 1965 2 Sheets-Sheet 2 3 J /Z 35 .750! 2 Z /J0 Z0 United States Patent Office 3,336,543 ELLIITICAL WAVEGUIDE CONNECTOR Ernest H. Johnson, Chicago, and Peter F. Van Dyke, Palos Park, Ill., assignors to Andrew Corporation, Orland Park, Ill., a corporation of Illinois Filed June 7, 1965, Ser. No. 461,821 9 Claims. (Cl. S33-95) This invention relates to electrical connectors, and more particularly to a connector construction for coupling a flexible elliptical waveguide to another transmission element such as a rectangular waveguide.

Elliptical waveguide is now commercially available in the form of a flexible helically corrugated elliptical tube. (It will be understood that the terms ellipse and elliptical as herein used do not necessarily refer to figures meeting the mathematical definition of these terms, but refer only to the generally oval shape sometimes called elliptoid, and, similarly, the references herein to major and minor axes refer only to the longer and shorter transverse dimensions of such a shape, the mathematical formulae relating to the parameters of a true ellipse being immaterial to the present invention.)

Various forms of connectors have heretofore been employed for flexible waveguide, bearing more or less similarity to the type of connection used with rigid waveguide, employing a flange or similar termination to which the end of the guide is secured by silver-solder or in some analogous fashion. Normally, flexible waveguide, used in long lengths taken from reels in a manner similar to the use of cable, is coupled at its terminal ends to conventional rectangular waveguide provided on the equipment coupled by the guide (such as transmitter and antenna, etc.). Such coupling requires a transition section, which is coupled at one end to the elliptical guide and at the other end to the rectangular guide, as in normal waveguide practice involving series connection of guides of differing size or configuration;

The application to the end of a waveguide of a connecting flange by soldering and similar operations is impractical for performance in the field with the requirements of electrical continuity and gas seal which must be met. Accordingly, these have been devised structures I adapted to be installed on the cut-olf end of flexible waveguide without requiring such soldering. Such a structure is shown in German Patent 1,165,121, the terminating structure being clamped to the end of the guide by the tightening of bolts, and having a front end surface similar to that of a waveguide flange, for attachment to the corresponding flange of a transition section, which is in turn fastened, in similar fashion, to a rectangular waveguide.

Despite such structures as just mentioned, the lield installation of elliptical waveguide cut from a long length at the point of use has remained until now both diiiicult and expensive as regards parts and complexity of the operations involved, and this constituted, prior to the present invention, a substantial impediment to the full use of flexible waveguide in a manner generally similar to the use of electrical cable, cut off to length at the point of installation. It is the general object of the present invention to provide a waveguide connector construction overcoming this impediment to more widespread use of flexible waveguide as a transmission medium.

This object is accomplished in the present invention by the provision of a construction having a number of novel features which cooperate to reduce the oost and 3,336,543 Patented Aug'. 15, 1967 complexity of the connector hardware and of the installation thereof, to a point comparable with the analogous portions of a cable system.

In the present invention, there is provided a combined end attachment and transition fitting which is highly compact, has very few parts, and may be fully assembled and disassembled by the operation of a single clamping nut of a general type analogous to those used with cable, the clamping action by which the end of the waveguide is secured to the connector by the tightening of this nut at the same time coupling the guide t-o the transition region. The clamping nut is also made gas-tight in being secured. The end of the guide abuts directly against the opening of the transition region, thus minimizing the number of joints in the assembly and correspondingly minimizing the reflections which are inherently multiplied with the number of joints.

The transition region of the present connector combines compactness, ease of fabrication, and electrical eiiiciency in a highly advantageous manner. The transition between the fundamental transmission mode of the elliptical guide and the fundamental transmission mode of the rectangular guide is performed by a novel shaping of the interior in such a manner as to fold or telescope the transition of shape and the transition of size into a single longitudinal region of novel configuration accomplishing the transition with a low length requirement for any give efliciency of performance.

For understanding of the improvement'eifected by the invention in connectors for the purposes mentioned, reference is made to the particular embodiment selected for illustration in the drawing, in which:

FIGURE l is a longitudinal sectional view taken along the line 1-1 of FIGURE 3, showing an elliptical waveguide connector made in accordance with the invention, with the end' of a waveguide installed therein;

FIGURE 2 is an elevational view of the connector of FIGURE 1 at the end thereof designed for connection to a rectangular guide;

FIGURE 3 is a view in section taken along the line 3 3 of FIGURE 1;

FIGURE 4 is a View corresponding to a portion of FIGURE 1, but illustrating a clamping nut shown therein in the unfastened or withdrawn position;

FIGURE 5 is a sectional view taken along the line 5`5 of FIGURE l;

FIGURE 6 is a longitudinal sectional view of a transition portion of the connector, taken along the line 6 6 of FIGURE 3; and

FIGURE 7 is a transverse sectional view taken along the line 7-7 of FIGURE 6.

The illustrated connector consists generally of a transition body 10 and an end-connecting portion 12 holding the end of an elliptical waveguide 14.

The inner end of the transition body 10 is externally threaded at 16 and engages the internal thread 18 of a tubular clamping nut 20 which extends out over the end of the guide 14.

Nested into the circular interior of the nut 20 is a clamping bushing 22, externally circular and having an aperture 24 of elliptical shape passing with small clearance the helically corrugated body 26 of the guide 14. At the extreme end of the guide, a large number of tabs 28 formed by slitting are ybent over against the surrounding surface of the bushing 22. An internal shoulder 30 on the nut 20 engages the outer edge of the bushing 22 and securely clamps the tabs 28 against the facing end of the transition body 10.

This end of the transition is formed with a mouth 32 which is generally elliptical but has slight notch-like irregularities 34 at the regions representing longitudinal projections of the corners 34a of a rectangular mouth or termination 36 at the opposite end of the transition. The elliptical opening 32 is of a sie and shape corresponding to the average of the root and crest configuration of the elliptical guide 26, this average size relation being found to be the best match to the helically corrugated guide.

The shaping of the interior of the transition aperture is that of the outer surface of the geometric figure formed by the common center positioning of a tube constituting a uniform projection of the rectangular mouth 36 with a tube of tapered elliptical cross-section having major and minor axes linearly decreasing along the length, being the axes of the elliptical mouth 32 at the inner end and being of major and minor axes corresponding to the longer and shorter dimensions of the rectangular mouth 36 at the outer end. As will be observed upon study, the figure thus produced consists of corners 34b constituting projections of these portions of the mouth 36, and outwardly bowed elliptical arcs 38 and 40 in the shorter and longer sides, respectively, representing the major and minor axes which diminish along the length, increasing the size of the corner portions 34b until the elliptical portions disappear entirely at the extreme end, as indicated at 41 and 41a. As will -be seen, this configuration produces corners or notches 34 at the elliptical mouth end which vary in magnitude with the relation of the major and minor axes to the dimensions of the rectangular mouth at the opposite end, which are of course shorter than the respective axes with which they are aligned, because of the relation of these dimensions in guides of the two shapes designed for the same frequency range. The precise ratios of dimensions of elliptical and rectangular ends are not necessarily precisely constant. It is experimentally found, however, that the shaping of the interior in the manner just described produces highly satisfactory results with guides of both shapes -designed for the same frequency range over a considerable range of designs of the individual ends. The irregularities at the elliptical mouth formed by the corners 34 may be made substantially larger than illustrated without producing serious reflections at the interface, where the elliptical mouth is smaller relative to the rectangular mouth than in the illustrated connector. In the case of variation of the relative dimensions in the opp-osite direction, the small irregularities at 34 disappear, but this does not affect the proper shaping as above described, merely producing a small longitudinal region at the inner end in which the cross-sections are elliptical, until the point at which the corner irregularities of the cross-section first appear.

It is found that this shaping produces great relative ease of fabrication as compared with performing these transitions in different longitudinal sections, in addition to being more ef'licient for any length than known transition designs in whch shape and size transitions are made serially.

The alignment of the guide 14 with the elliptical mouth of the transition body is maintained by a locating pin 42 in the latter which may be seated in one or the other of opposed socket bores 44 n the face of Ithe bushing 22. The provision of the selectively used opposed bores 44 makes it unnecessary, in making an installation, to be concerned about producing an upside down relative orientation of the end of the guide and the body 10, which could otherwise occur if the end of the guide is to be assembled with the bushing 22 at both ends of a long run before the guide is hung with the bodies already installed. This selection of orientation is made particularly important to convenience by the provision of a gas port 46 in the body 10, for which. one orientation or another may be desired in a particular installation. The port 46 is of course normally plugged (not shown) when not used for permanent connection of a filling or exhaust gas line.

The illustrated connector provides for forming gas seals at the ends of the nut 20 in a simple and convenient manner. An O-ring 48 is seated in a groove 50 in the outer surface of the body 10 adjacent to the threads 16. When the nut 20 is in its tightened condition (FIGURE l), this ring is tightly compressed by the inner end surface 52 of the nut 20, which is offset slightly radially outwardly with respect to the internal threads 18 adjacent thereto. A similar O-ring 54, seated in a groove 56 on the internal surface of the opposite end portion of the nut 20 is, in the tightened condition of the nut, tightly compressed against the outer surface of the bushing 22.

This tight compression of the O-rings 48 and 54 to form the gas seals is accomplished in the operation of tightening the nut without introducing difficulty in starting `the nut. The starting condition is shown in FIGURE 4, where it will be seen that the nut 20 is withdrawn from the threaded engagement. In this condition, the O-rings 48 and 54 are contacted only by the respective members on which they are seated, and no contact with them is made by the opposite member until the threading is substantially advanced. The nut may thus lbe started with virtually no requirement of exertion of force by the fingers. When the nut is advanced to the point where the rings 48 and 54 are contacted by the opposite member and begin to be compressed, further tightening of the nut is accomplished by the use of a wrench on flats 57 provided on the nut for this purpose; in this manner, the rings are tightly compressed (the edges of the bushing 22 being slightly rounded or bevelled to facilitate the compression), and the terminal portion of the tightening then clamps the tabs 28.

A gas seal is also provided to prevent gas leakage along the internal surface of the bushing 22. In the illustrated embodiment, this is done by filling the voids created by the outer configuration of the corrugated body 26 with an adhesive sealant, such as a polysulfide or epoxy. The plastic protective jacket 60 on the guide is stripped back to the point of entry of the guide into lthe bushing 22, and its end is sealed to the end of the bushing by :the excess sealant. This seal is of course made as one of the first steps of assembly, with the nut 20 withdrawn along the length of the guide, the forming of the tabs 28 also being done at this stage. To prevent the application to the tab joints of stresses due to bending of the guide at the joint with the connector, the bushing has a longitudinal extension or thickness at least half the minor axis of the elliptical guide.

At the rectangular end, the transition is of course provided with a conventional apertured flange 62 with a gasket groove 64, seating a gasket 466. In the present construction, this gasket is preferably designed so that the fiange may be used interchangeably for either a joint of the continuous or butt type or of the choke type, as determined by the mating fiange used on the equipment t0 which the connection is made.

The embodiment illustrated in the `drawing and described above is a commercial construction which has been found highly satisfactory. However, the teachings of the invention are of course not limited to the particular embodiment selected for illustration to conform with the requirements of the patent laws. Persons skilled in the art will readily make many adaptations of both the overall combination and the various inventive features thereof for use in constructions substantially different in appearance and detail from that herein illustrated. Accordingly, the scope of the protection to be given the invention should not be determined on the basis of this particular embodiment, but should extend to all utilization of the teachings of the invention as defined in the appended claims, and equivalents thereof.

What is claimed is:

1. An elliptical-to-rectangular waveguide transition connector comprising:

(a) a circular clamping bushing having an elliptical aperture adapted to receive the end of an elliptical waveguide and of longitudinal thickness greater than half the minor axis of the aperture,

(b) a transition body having a longitudinal aperture generally elliptical at the inner end'and substantially rectangular at the outer end, the major and minor axes of the ellipse being aligned respectively with the longer and shorter dimensions of the rectangular gaperture, and each axis being longer than the respective rectangular dimension,

(c) the interior of the aperture being in the shape of the Iouter surface of the geometric figure lformed by the common-center positioning of a tube of uniform rectangular cross-section of the dimensions of the outer end of the aperture with a tube of tapered elliptical cross-section having major and minor axes linearly diminishing along the length from the major and minor axis dimensions of the elliptical aperture at the inner end to the corresponding dimensions of the rectangular aperture at the outer end,

(d) the inner end of the body being in rotationally keyed engagement with the bushing to align the elliptical apertures therein,

(e) threading on the circumference of the inner end of the body,

(f) a clamping nut having an inner end portion engaging the threading on the body and an outer end portion abutting against the bushing to clamp the iiared end of a waveguide between the bushing and the body,

(g) and O-rings compressed between the inner surface of the clamping nut and the outer surfaces of the body and the bushing, respectively, to form gas seals therebetween, each O-ring being seated in a groove in one of said surfaces and contacted by the other surface only upon tightening of the threaded engagement.

2. An elliptical-to-rectangular waveguide transition connector comprising:

(a) a clamping member having an elliptical aperture adapted to receive the end of an elliptical waveguide,

(b) a transition body having a longitudinal aperture generally elliptical at the inner end and substantially rectangular at the outer end, the major and minor axes of the ellipse being aligned respectively with the longer and shorter dimensions of the rectangular aperture, and each axis being longer than the respective rectangular dimension,

(c) the interior of the aperture being in the shape of the outer surface of the geometric ligure formed by the common-center positioning of a tube of uniform rectangular cross-section of the dimensions of the outer end of the aperture with a tube of tapered elliptical cross-section having major and minor axes linearly diminishing along the length from the major and minor axis dimensions of the elliptical aperture at the inner end to the corresponding dimensions of the rectangular aperture at the outer end,

(d) and means for holding the clamping member against the inner end of the transition body.

3. An elliptical-to-rectangular waveguide transition having a longitudinal aperture generally elliptical at one end and substantially rectangular at the other end, the major and minor axes of the ellipse being aligned respectively with the longer and shorter dimensions of the rectangular aperture, and each axis being longer than the respective rectangular dimension, the interior of the aperture being in the shape of the outer surface of the geometric gure formed by the common-center positioning of a tube of uniform rectangular cross-section of the dimensions of the rectangular end of the aperture with a tube of tapered elliptical cross-section having major and minor axes diminishing along the length from the major and minor axis dimensions of the elliptical aperture to the corresponding dimensions of the rectangular aperture.

4. The transition of claim 3` wherein the diminishing of the major and minor axes is linear.

5. An elliptical-to-rectangular waveguide transition having a longitudinal aperture generally elliptical in one portion and generally rectangular in another portion, the major and minor dimensions of the ellipse being aligned respectively with the longer and shorter dimensions of the rectangle, the intermediate portion being of the crosssectional shape of the outermost conliguration of the geometric igure formed by the superposition of an elliptical shape and a rectangular shape.

`6. An elliptical-to-rectangular waveguide transition having a longitudinal aperture generally elliptical at the inner end and generally rectangular at the outer end, the major and minor axes of the ellipse being aligned respec tively with the longer and shorter dimensions of the rectangular aperture, the interior of the aperture being in the shape of the outermost surface configuration of the geometric iigure formed by the common-center positioning of a tube of Irectangular cross-section with a tube of elliptical cross-section, at least one being `of diminishing dimension with increase of distance from the correspondingly shaped end.

7. An elliptical-to-rectangul-ar waveguide transition connector comprising:

(a) an externally circular clamping bushing having an elliptical aperture adapted to receive the end of an elliptical waveguide,

(b) a transiti-on body having fa longitudinal aperture generally elliptical at the inner end and substantially rectangular at the outer end,

(c) the inner end of the body being in rotationally keyed engagement with the bushing to align the elliptical apertures therein,

(d) threading on the circumference of the inner end of the body,

(e) land a clamping nut having an inner end portion engaging the threading on the body and an outer end portion abutting against the bushing to clamp the flared end of a waveguide between the bushing and the body.

l8. A waveguide transition connector for liexible waveguide comprising: l

(a) an externally circular clamping bushing having a non-circular aperture adapted to receive the end of a liexible waveguide,

(b) a transition body having a longitudinal aperture generally conforming to the shape of said non-circu- 1=ar aperture at the inner end and of a second configuration at the outer end and shaped to form an intermediate transition region,

(c) threading on the circumference of the inner end of the body, said end being in rotationally keyed engagement with the bushing to align the apertures therein,

(d) and a clamping nut havin-g an inner end portion engaging the threading on the body and an outer end portion abutting against the bushing to clamp the flared end of a waveguide between the bushing and the body.

9. A gas-sealed electrical connector comprising:

(a) an end-mounting portion adapted to receive the end of a tubular conductor having a gas passage therethrough,

(b) a body having a tubular aperture,

(c) threading on the circumference of the inner end of the body,

(d) a clamping nut having an inner end portion engaging the threading on the body and an outer end portion abutting -against the end-mounting portion to clamp the ared end of the tubular conductor against the body, and

(e) a rst resilient ring compressed between the inner surface of the clamping nut and the outer surface of the body and a second resilient ring compressed between the inner surface of the clamping nut and the end-mounting portion to form gas seals therebetween, each resilient ring being seated in a groove in one of said surfaces and contacted by the other surface only upon tightening of the threaded joint beyond the initial engagement thereof.

References Cited UNITED STATES PATENTS 2,540,012 1/1951 Salati 333--97 2,845,601 7/1958 Jaffe 333-97 2,858,512 10/1958 Barnett 333-98 2,870,420 1/1959 Malek 333-97 2,937,360 5/1960 True 333-97 FOREIGN PATENTS 1,099,602 2/1961 Germany.

785,199 10/1957 Great Britain.

HERMAN KARL SAALBACH, Primary Examiner.

L. ALLAHUT, Assistant Examiner. 

5. AN ELLIPTICAL-TO-RECTANGULAR WAVEGUIDE TRANSITION HAVING A LONGITUDINAL APERTURE GENERALLY ELLIPTICAL IN ONE PORTION AND GENERALLY RETANGULAR IN ANOTHER PORTION, THE MAJOR AND MINOR DIMENSIONS OF THE ELLIPSE BEING ALIGNED RESPECTIVELY WITH THE LONGER AND SHORTER DIMENSIONS OF THE RECTANGLE, THE INTERMEDIATE PORTION BEING OF THE CROSS- 